From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15623606A31A for ; Wed, 28 Oct 2026 13:50:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=AKVRO4a5; dkim=pass (2048-bit key, unprotected) header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=BxUepWxa DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=EKOJSvQCyvmegciiDSA3qkq54znl6sRsTPqc7BTTnKg=; b=AKVRO4a5ZOAdb5vy8j5mK0ZKtY MsK2AIEcSV7uX2L2FTrUS+nxnkwhspzVDIcmnt59ezfpSQY8t0UBaYJZ5+DDeyz1NZyT9kRyCyBlM fSOsYgvVC2FOnI/MwXoO/Z0dC+ICaieqmmwLxnnbE7lGIhmXfVEIgZGUSM21bpakI8oY8eXcZvoN+ dltyO06wn9g3nQZAyef5mbLAEkcAU6CK4GCW7Uqo8vr4B9gv47D34I6Txj0ltks7CkNW8R5Eqt5th 9vmA6XpiUOVRH9SMKTKUwMGtnhb0w0sbKWmIBe56D7awy1RYhRaF/VGd3YmZkdufNdesM0MbZkLRm qyvAib7Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM42b-000000077Gc-00qH; Wed, 28 Oct 2026 13:50:09 +0000 Received: from stravinsky.debian.org ([2001:41b8:202:deb::311:108]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM42Z-000000077Fp-12gV; Wed, 28 Oct 2026 13:50:08 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=EKOJSvQCyvmegciiDSA3qkq54znl6sRsTPqc7BTTnKg=; b=BxUepWxaQM94nl47RKcbqrBwZ7 kKjKjVjHXt+ZcHaBoC9nDp4oSN9ak/TO/XSgZcZWwNyUes07CsiuLocLH66v0bHNVj9IKB35ZiIBf fXcJPdkUhdzi3eVA3yYx2Wb11fbpqdcML3ik3qmNvo9oHUT+1pIV40JNfxDMJ/wmX9eR2jxICexSE ad3Hc1No0hfI+y0IgWiVtZAg0BshCR6qLOZqqp16nouHynXTJ9IQB4qiaP3+hFCWqYSQ+ZvQao6uQ gtgCbH3J+tJpJRCI+onTodJWcxHXBKOxtmizI01tTt3GIKNO4zPmrK05hh4otiSxEU/f4XlZ4mWb4 KFvceyFg==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1xM41u-002Ho4-0T; Wed, 28 Oct 2026 13:49:26 +0000 Date: Wed, 28 Oct 2026 06:49:18 -0700 From: Breno Leitao To: "David Hildenbrand (Arm)" Cc: Mike Rapoport , Ard Biesheuvel , Ilias Apalodimas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Catalin Marinas , Will Deacon , Mark Rutland , kas@kernel.org, kexec@lists.infradead.org, Brendan Jackman , Johannes Weiner , Zi Yan , shakeel.butt@linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-arm-kernel@lists.infradead.org, rmikey@meta.com, riel@surriel.com, harry@kernel.org, kernel-team@meta.com Subject: Re: [PATCH v6 4/7] mm/memblock: add a reserved-region flag for poisoned frames Message-ID: References: <20261016-hwpoison-kho-v6-0-f304255147da@debian.org> <20261016-hwpoison-kho-v6-4-f304255147da@debian.org> <524ee7d9-790d-48b6-8613-841da042c32a@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <524ee7d9-790d-48b6-8613-841da042c32a@kernel.org> X-Debian-User: leitao X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261028_065007_293820_1B28BE9A X-CRM114-Status: GOOD ( 19.70 ) X-Spam-Score: -4.4 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, Oct 28, 2026 at 09:39:42AM +0100, David Hildenbrand (Arm) wrote: > On 10/22/26 18:33, Mike Rapoport wrote: > > Hi Breno, > > > > On Fri, Oct 16, 2026 at 05:15:44AM -0700, Breno Leitao wrote: > >> memblock allocates from and frees to buddy whatever is not reserved, and > >> knows nothing about frames an earlier kernel found hardware-poisoned. > >> Such a frame can back the memmap, a page table or a percpu area before > >> any hwpoison code runs, and otherwise reaches the buddy allocator like > >> any other free frame. > >> > >> Add MEMBLOCK_RSRV_HWPOISON for a reserved range holding those frames. > > > > How much this would fragment memblock.reserved? > > > > memblock is not very scalable, to say the least, and each new flag > > increases the size of memblock arrays which obviously hurts performance. > > I assume that if you have too many regions there, you have different problems > than scalability problems. > > We should cut out larger chunks, and if they are all over your address space you > should scrap that machine. Ack, that is what the 2M unit does. A DRAM row fault shows up as many 4K pages but lands in one or two units, and adjacent units share one memblock.reserved region. Mike, on the statistics you asked for: across the Meta hosts that logged a hard memory failure in the last 28 days, these are the memblock.reserved regions each host would need: p50 p90 p99 x86 1 4 41 arm64 1 5 27 Thanks, --breno